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Solar Viewing w/refractor


Liquid360

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The FSQ106 is a petzval, so as Shane says it's not suitable for a Herschel Wedge or Daystar Quark.

You could however use your 90mm I think, is that not an ED doublet? If it is then the wedge would give you white light and a quark, Ha.

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Cheers Stu

cannot see signatures on phone

Me neither Shane :-), just going from memory of Liquid360's setup pic which, I think, had a Stellarvue 90 on top of the Tak FSQ. Looked v nice :-)

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If you mean white light solar then assuming your scope does not have a petzval design and is all metal then a lunt wedge would provide superb views with the appropriate filters

What's a petzval design, Shane? I'm completely ignorant of the term :rolleyes2:

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A Petzval design has an extra lens group in the rear which acts as built-in reducer and flattener. This may overheat and shatter when it receives the full heat of the sun. Even with a front-mounted ERF you may get too much energy on that lens. Petzval designs also don't work well with most telecentric barlows (like the one in the Quark). You can of course use solar film (cheap and cheerful, works well), or a front-mounted etalon (RATHER more expensive).

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Rob, it is a Quadruplet design which has a doublet at the front and another doublet just ahead of the focuser.

The second doublet acts as a reducer and flattener giving a wide, flat field which is good for imaging.

I have a Genesis which is a 101mm petzval design. The front doublet is an achro of around f11 I believe, the rear element reduces this to f5 with a nice flat field. I can get a 5 degree field with it.

The issue with solar is that the rear doublet is usually cemented, and is closer to the focal point so the heat build up is more significant and can cause damage. You should use a D-ERF infront of the objective with petzval designs scope for solar Herschel wedge or Quark use

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Sorry if I'm derailing the thread! And thank you so much for the replies!

So, how do you guys know if a frac is petzval or not? I mean, I'm not that clued up but when I see fracs for sale I just see achros, apos, ED, triplets etc. Does it say specifically on the 'box' when you buy? Or do you guys just know from the look?

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Rob, it is a. Quadruplet design which has a doublet at the front and another doublet just ahead of the focuser.

The second doublet acts as a reducer and flattener giving a wide, flat field which is good for imaging.

I have a Genesis which is a 101mm petzval design. The front doublet is an achro of around f11 I believe, the rear element reduces this to f5 with a nice flat field. I can get a 5 degree field with it.

The issue with solar is that the rear rear doublet is usually cemented, and is closer to the focal point so the heat build up is more significant and can cause damage. You should use a D-ERF infront of the objective with petzval designs scope for solar Herschel wedge or Quark use

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Herschel wedge, maybe, but the tele-centric system in the Quark might not work well with it.

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Sorry if I'm derailing the thread! And thank you so much for the replies!

So, how do you guys know if a frac is petzval or not? I mean, I'm not that clued up but when I see fracs for sale I just see achros, apos, ED, triplets etc. Does it say specifically on the 'box' when you buy? Or do you guys just know from the look?

Typically, Petzvals are longer than you would expect from the focal ratio, often they are marketed as quadruplets (or Petzvals), and finally, an extra lens group should be visible from the rear

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Herschel wedge, maybe, but the tele-centric system in the Quark might not work well with it.

No, fair enough Michael, I was only thinking about the heat issue rather than whether the Quark would actually work!!

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Wow! Thank you so much for the swift replies. I've never heard this term before, so thank you Michael and Bik Mak for going through it with me. I imagine being a quadruplet, these designs are really quite expensive and more suited for imagers rather than visual users. Is that a fair understanding?

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Wow! Thank you so much for the swift replies. I've never heard this term before, so thank you Michael and Bik Mak for going through it with me. I imagine being a quadruplet, these designs are really quite expensive and more suited for imagers rather than visual users. Is that a fair understanding?

I think that is probably a fair statement, particularly for scopes like the Taks, and say the TV 101NP and 127is. They are designed to give a large image circle with a flat field. I guess it removes the hassle of reducer/flattener and getting the spacing correct.

I use my Genesis entirely for visual. I believe Al Nagler pioneered the concept, and enjoyed the flat widefield views it gave when panning across the Milky Way. That is something I really enjoy too. The scope is a 4" f5, 500mm focal length and whilst it is not an apo, the correction is more like that of an f10 or so. You can use shorter focal length eyepieces whilst still getting wide fields and the smaller exit pupil really helps improve the contrast by darkening the sky background.

Under a dark sky the Veil and North America nebulae fit easily within the fov and look pretty spectacular.

Apologies, this has wandered some way from Solar!!

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That is a great explanation, Big Mak and thank you :smiley: They certainly sound like a lovely telescope, especially at a relatively dark site with all those little gems glittering. It's funny how some things slide through the radar and only picked up on at a later date. I mean, I guess you guys (yourself, Jules, Marki and John etc) have talked about the Petzval scopes before but for some reason I've never hooked onto the term.

Swinging this back to a solar viewing thread :p , now I'm working again, I'm trying to decide whether to save this year for a Lunt 50mm or go for a quark and a small fast apo (70mm to 80mm) which could double as a milky way scanner and cluster framer :grin: The pocket says the former but there's something alluring about the extra aperture and flexibility of the latter which could double as a neat little travel scope (when going by plane).

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Well.... I've opted for a Quark rather than the Lunt 50. Time will tell if it turns out to be a wise choice.

For me, I wanted to be able to take advantage of the TV85 for more resolution. I have also bought a Tak 60 to get lower power, full disk views which should still rival the L50. Makes for a neat travel setup too, I could take a photo tripod, mini giro, Herschel wedge, quark and which ever scope I could fit in. Hoping to get away on holiday for a late break in October/November so will put it to the test.

There, I think we got that back into solar without anyone noticing ;-)

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For me, I wanted to be able to take advantage of the TV85 for more resolution. I have also bought a Tak 60 to get lower power, full disk views which should still rival the L50. Makes for a neat travel setup too, I could take a photo tripod, mini giro, Herschel wedge, quark and which ever scope I could fit in. Hoping to get away on holiday for a late break in October/November so will put it to the test.

Aye, it's exactly this kind of reasoning that makes the quark such an appealing purchase. So long as the gear packs down to small suitcase size, it looks like a very reasonable travel set up which could be stored away in one of the cabins of a flight. Back at home, I would have thought the resolution from a 60mm quality apo and quark would at least equal the 50mm Lunt but then that very quark can be lifted over to a 100mm (Russian achro :p ) for an even bigger buzz  :grin: Sure, some kind erf would be needed, but I'm sure they're not that expensive. 

Liquid 360, if you've got any more questions or doubts, just fire them out :grin: As you see, there are some seriously wonderful folk here at SGL who really do know their stuff. Furthermore, from your own original question, I too have learnt something new today. I think so long as we're polite and thoughtful to each other, you know, just acting like decent human beings, there should be no question of being banned :smiley:

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I really appreciate it!! In the coming days I'll have so many questions. I've leapt into the deep water which is how I like it. I'm thankful I asked before pointing my scope at the sun and paying the price for ignorance.

I'll be seeing you guys often I imagine!

Thankfully

Nate

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This is an enjoyable thread to read as many members will gain information especially as the Quark has opened up so many extra opportunities. I have used Orion and Thousand Oaks glass filters plus Baader solar film for many years on my refractors. However, 18 months ago I bought a 1.25" Lunt Herschel Wedge together with a Baader Continuum Filter and the view of the Sun using Binoviewers blew me away. As Stu and Michael has already stated you need to be careful with certain type of refractors - Petzval design. In addition the HW works best with refractors of 6" or less.

Many solar observers have been using white light and Ha together especially with the quality of Ha scopes coming from Coronado, Lunt and others. The amount of interest that the new Lunt 50mm introduced a few months back was amazing and many members were getting ready to buy this model until the Quark came on the seen.

As Stu has already indicated a good quality doublet gives fantastic white light views with the Herschel Wedge and then to be able to use the same scope with the Quark just adds to the system. This same scope can then be used for night time viewing - brilliant.

To add to the pleasure a small quality doublet 60/70 mm makes a great travel scope to take to eclipses and add the HW and Quark - gives you so many observing opportunities.

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So just to make sure I've got this right, as I have a very real fear of either burning my eyes out or even worse damaging my hardware, it's a big no on using the FSQ and its petzval design optics, but my SV90 would do this trick with a good glass filter?

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Which model Stellarvue is it, a triplet apo?

Maybe worth just checking with Stellarvue that it's ok. If it's an air spaced triplet then it should be ok but oil spaced or cemented triplets are a no no unless you have a full aperture filter (glass or Baader solar film) covering the objective.

Assuming it is ok, you need a Herschel Wedge, Lunt 1.25" is good, with an ND 3.0 filter fitted and either a polarizing filter and/or a Continuum filter.

The ND3.0 is often ready fitted in the wedge but it's important you check. The continuum filter goes in the barrel of the eyepiece as a further brightness reduction and narrowband filter to bring out the detail.

For Ha, the simplest way is to use a Daystar Quark which would fit into a diagonal with a UV/IR cut filter in the objective side to reduce the heat. Best eyepiece options are TV Plossls, probably 32mm to get best fov.

There are other, more expensive options but I know less about these.

Last thing to say, please don't take my advice alone, please seek advice and safety guidance from whichever retailer you use and make sure you fully understand the risks and requirements to make sure you put the elements together properly.

Stu

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I had to look it up to be sure, but it is a SV90mm Apo Triplet Raptor. I'm assuming the "raptor" portion is marketing and has little to do birds or pray or dinosaurs, but it is made of carbon fiber which, as we all know, is a velociraptors composite material of choice.

I'll drop Stellarvue an email, good idea. Also they have liability insurance should I follow their instructions and burn out my retina.

When it comes to looking at the sun, I believe this is one of those instances, when trying to be economical is a bad move.

I sooo appreciate the help/advice!!!

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